react-native - es6:导出后如何导入const？

Question

我为我缺乏知识而道歉。我想在文件内导入const值。我在同一目录中有两个文件Home.js和styles.js。

Home.js

import React from 'react';
import styles from './styles';

const Home = (props) => {

    const HEADER_MAX_HEIGHT = 200;

}

export { HEADER_MAX_HEIGHT };
export default Home;

And in styles.js

import { StyleSheet } from 'react-native'
import { HEADER_MAX_HEIGHT } from './Home';

export default StyleSheet.create({
    header: {
        height: HEADER_MAX_HEIGHT
    }
});

但我收到此错误

Can't find variable : HEADER_MAX_HEIGHT

如何在styles.js中访问该变量？

Answer 1

尝试:

Home.js

import React from 'react';
import styles from './styles';

export const HEADER_MAX_HEIGHT = 200;

const Home = props => <h1>Home</h1>;

export default Home;

styles.js

import { StyleSheet } from 'react-native';
import { HEADER_MAX_HEIGHT } from './Home';

export default StyleSheet.create({
  header: {
    height: HEADER_MAX_HEIGHT,
  },
});

您的 HEADER_MAX_HEIGHT必须在 Home.js文件中，但在 Home组件之外。您可以在这里阅读: Javascript Scope